Scala 3 scala:doc generation does not appear to work

[programmatix]

As far as I can tell, the scala:doc target cannot work?

To reproduce
I created a project with mvn archetype:generate -DgroupId=com.example -DartifactId=my-scala3-project -DarchetypeGroupId=net.alchim31.maven -DarchetypeArtifactId=scala-archetype-simple -DarchetypeVersion=1.7 -DinteractiveMode=false then tweaked it to use Scala 3 and latest version of the plugin:

git clone https://github.com/programmatix/scala-maven-plugin-issue-repo
cd scala-maven-plugin-issue-repo
mvn scala:doc -DdisplayCmd=true

Will output

...
[INFO] --- scala:4.9.5:doc (default-cli) @ my-scala3-project ---
bad option '-doc-format:html' was ignored
bad option '-doc-title' was ignored
source file not found: my-scala3-project 1.0-SNAPSHOT API
2 warnings found
1 error found
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  0.674 s
[INFO] Finished at: 2025-08-12T16:31:08+01:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal net.alchim31.maven:scala-maven-plugin:4.9.5:doc (default-cli) on project my-scala3-project: wrap: org.apache.maven.reporting.MavenReportException: wrap: Process exited with an error: 1 (Exit value: 1) -> [Help 1]

Investigation
I had a bit of a look through the code. (But I don't have too much experience either with this plugin or with Scala 3 scaladocs, so I may have made a mistake here.)

I see there is some Scala 3 support, in that we switch to using dotty.tools.dotc.Main in Scala 3 mode (which happens here). But AFAICT, that tool can't be used directly to produce Scaladocs? And these two files don't seem to have been updated anyway to produce Scala3-compatible scaladoc CLI args:

https://github.com/davidB/scala-maven-plugin/blob/master/src/main/java/scala_maven/ScalaDocJarMojo.java
https://github.com/davidB/scala-maven-plugin/blob/master/src/main/java/scala_maven/ScalaDocMojo.java

[slandelle]

There was some ongoing work on scaladoc 3 that never landed: #611
Maybe you could resurrect this work?

[programmatix]

@slandelle thanks for the swift response, and confirming this is a known problem.

I don't have too much experience with Scala 3 yet, so I'm not sure if I feel confident taking that on currently. Maybe at some point in the future. I have tried some experimental approaches today, like getting the plugin to call dotty.tools.scaladoc.Main instead, but haven't got anywhere useful.

[slandelle]

I'm not using Scala 3 either so I can't help.